I am in week 11 of having a cough that gets worse at night. Its more a tickly throat but then at night the cough is so bad I struggle to breathe and gasp for air. I've been to doctors who gave me an inhaler and anti-hystimenes. This hasn't helped. A phlegm test came back clear. My chest xray was clear. I took cough medicines which have still not helped. I really can't cope with any more sleepless nights. What else could I try?

I am sorry to hear that you have been unwell. The first thing which comes to my mind is that you may have a form of mild asthma. I do not know what your doctors have said to you, but you mention an inhaler and they might be thinking along the same lines.
 
Whatever the inhaler is for, it does not seem to be helping you and what you should do is to go back to your doctors to let them know that you are still unwell - they should either confirm the diagnosis or consider other possibilities for your symptoms.

There are other medicines that can be used to treat asthma - and more importantly, prevent these episodes from occurring.
 
I am sorry that I cannot be of more help to you at this stage, but hope that the information above is useful to you.